1. Technical Field
The present invention relates to methods and apparatus for organic waste disposal. More particularly, the present invention relates to improvements in the biological decomposition of organic waste materials.
2. Prior Art
It will be recognized that conventional flush toilets are wasteful of precious water resources while simultaneously polluting those same resources. Consequently, there have been numerous prior art attempts to develop dry toilets, or toilets which dispose of organic waste without the need for water and without polluting the environment. The most promising approach, in this regard, has been the biological conversion toilet wherein aerobic conversion of organic waste to carbon dioxide, ammonia, and water is achieved by mixing the waste material with a bed of well known biological conversion activator materials. The primary problem facing most dry closets which have adapted this approach is the inability to completely aerobically decompose the waste material. The result is an odor emitted from the toilet which is too objectionable for home use or other such applications.
In U.S. Pat. No. 4,263,135 to Yeagley, there is described a recognition of the source of the problem in prior art toilets of this type. Specifically, it is described that prior art biological conversion toilets mix organic wastes with the bed of activator material for too short a period of time to achieve complete decomposition. Yeagley's invention involves maintaining the mixture of organic waste and activator material in a state of constant agitation or stirring, in the presence of oxygen, until the humidity in the vessel drops below a predetermined level. Yeagley vaguely relates this vessel humidity to the moisture in the mixture which he describes as being the primary parameter intended to control the stirring time. Specifically, good contact between air (oxygen), wastes and bacteria is not possible when the mix is too wet. The percentage of moisture in the bioconverting mix should be 40-60% for optimum speed of reaction. If too much moisture is present in the waste material, the excess water interferes with the contact between the waste material, the oxygen and the bacteria; however, adequate moisture must be present in order for the bacteria to properly function in the decomposition process.
It has been discovered, however, that the vessel or container humidity level is not necessarily a true measure of the moisture content in the mixture. For one thing, the temperature in the vessel has a greater effect on the humidity level above the mixture than in the mixture itself, so that humidity measurements must be compensated for temperature in order to be accurate. Further, the oxygen required for aerobic decomposition is supplied from the ambient environment surrounding the toilet by establishing an air flow through the vessel with an exhaust fan. The ambient air humidity will, therefore, have a significant effect on the humidity within the vessel and will, therefore, further distort any "fixed" relationship between the moisture content of the mixture and the humidity in the vessel. On the other hand, ambient air of high humidity tend to increase the moisture level in the mixture to an undesirable level.
Another important aspect of achieving complete decomposition of organic waste in toilets of the type described is the stirring or agitating action. More particularly, it is important that the entire mixture of activator material and waste material be caused to flow continuously and that stagnant or dead spots be avoided. In the device disclosed in the aforesaid Yeagley patent, stirring is effected by two auger members carried on spaced parallel drive shafts which are motor driven. The auger members of adjacent shafts do not transversely overlap; that is, there is a space between them which is not directly stirred. Moreover, plural augers are substantially identical in size and shape. The result is a tendency for stagnant or unstirred regions to develop in the mixture.